A general stator of a DC brushless motor comprises pluralities of U-phase coils, V-phase coils and W-phase coils each including a wire wound around an outer periphery of an iron core with an insulator provided therebetween, the coils being sequentially arranged in a circumferential direction. Ends of the wound wires pulled out of radially inner ends of the coil are integrally connected to each other to form grounds (neutral points).
In a wire-connection structure of a motor disclosed by Japanese Patent Application No. 2005-254569 which was filed by the present applicant, an end of a wound wire having a rectangular cross-section and pulled out of each coil is bent into a U-shape, and the U-shape bent portions of the wound wires of the adjacent two coils are connected to each other by fusing the wound wires to opposite ends of a connecting terminal, thereby forming a neutral point. Also, in this Japanese Patent Application, the present applicant proposed a structure in which the end of the wound wire pulled out of each coil is connected by the connecting terminal between an outer partition wall and an inner partition wall of an insulator, thereby forming a neutral point.
In bending a circular cross-sectioned wire, the wire has no directionality bias. On the other hand, a rectangular cross-sectioned wire can be easily bent in two directions perpendicular to each of their surfaces, but it is difficult to bend the rectangular cross-sectioned wire in directions oblique to their surfaces. Therefore, when the rectangular cross-sectioned wire is employed as the wound wire, there is a problem: it is not possible to completely mechanize the operation of bending the end of the wound wire pulled out of the coil into a U-shape, and thus manual operation is required, greatly increasing the processing cost.
Further, a space formed between the outer partition wall and the inner partition wall of the insulator is potted with a synthetic resin in order to prevent the breaking and corrosion of the wound wire and the connecting terminal. In this structure, notches for passing the wound wire therethrough are formed in the outer partition wall and the inner partition wall. However, because the notches are plugged by the wound wire passing therethrough, unhardened synthetic resin charged into a space between the outer partition wall and the inner partition wall hardly leaks out of the notches.
However, the wire pulled out of the coil includes a scrap wire portion for providing a tension to the wire during the wire-winding operation. When the scrap wire portion is passed through the notches in the outer partition wall and the inner partition wall, there is a disadvantage: because the scrap wire portion eventually becomes needless after completion of the wire-winding, the scrap wire portion is cut from a portion between the outer partition wall and the inner partition wall and discarded. The notch formed in the inner partition wall for passing the scrap wire portion therethrough is open without being plugged by the wound wire during the potting. Thus the synthetic resin leaks out of the notch, thereby requiring an operation of wiping off the leaking synthetic resin.